ss -s命令 可以查看当前操作系统的tcp ,udp连接数
[root@VM-12-4-centos ~]# ss -s
Total: 320 (kernel 356)
TCP: 64 (estab 12, closed 30, orphaned 0, synrecv 0, timewait 30/0), ports 0
Transport Total IP IPv6
* 356 - -
RAW 0 0 0
UDP 18 10 8
TCP 34 25 9
INET 52 35 17
FRAG 0 0 0